The term is most frequently used for spur-of-the-moment, first-draft, collaborative efforts produced at fannish events such as parties or cons. These are often much more fun to participate in than to read afterward, resulting, as rich brown put it, in "a publication that is forced, stilted and unpleasant."

The so-called "classic" one-shots, published during the Laney/BurbeeInsurgency, were different because the participants usually brought previously drafted and even somewhat polished material to the pubbing session.

A fanzine produced (perhaps imagined and cut, perhaps just run and assembled) at a single session. A one-shot session is either the session at which this is done or, sometimes, the fen comprising the session. Originally it meant a publication actually, and avowedly, intended to have only the one issue, as distinguished from "periodicals" which fold after one issue and other fmz which don't indicate whether they're periodicals or non-recurrent pamphlets. One-shots may be produced to commemorate an occasion or take advantage of a gathering of fannish manpower; such are those put out when the cry "Let's put out a one-shot fanzine!" arises. Or they may be intended to deal with their subject thoroly enough not to require further issues — bibliographies and works such as this one fit here. The most famous one-shot sessions were the four at which various issues (1,3,5,7) of WILD HAIR were produced; the Insurgents seem to have been responsible for designation of periodicals as one-shots when they were produced at a one-shot session.